Abstract: Based on the long-term continuous detection of the gas change in gob by using beam tube monitoring system,combined with SF6 tracing gas technology,the air leakage condition in gob was tested on No.154307 workface of Fenghuangshan coal mine which firstly using gob-side entry retaining with Y-type ventilation.The results indicated that the air leakage scope in gob was wide and the amount of air leakage was large in gob-side entry retaining with Y-type ventilation.Within a distance of 400 m to the workface,the oxygen content was about 20% with air leakage velocity of 0.027～0.075 m/s,being a rapid change area of wind speed.At a distance over 400 m to the workface,the oxygen content was about 16% with air leakage velocity of 0.017～0.024 m/s,being a slow change area of wind speed.